Polarization-dependent manipulation of optical properties in a tripod system

Abstract

We analyze the dependence of the transmission profiles of an atom in a tripod configuration on the polarizations of the coupling and the probe beams and use room-temperature metastable helium (${}^{4}$He*) as a model system. We show that, by rotating the orthogonally polarized coupling-probe beams with respect to an applied small magnetic field, one can manipulate the detuned peaks due to electromagnetically induced transparency [Kumar, Laupr\^etre, Ghosh, Bretenaker, and Goldfarb, Phys. Rev. A 84, 023811 (2011)] and the central peak arising because of ground-state coherent population oscillations [Laupr\^etre, Kumar, Berger, Faoro, Ghosh, Bretenaker, and Goldfarb, Phys. Rev. A 85, 051805(R) (2012)] observed earlier separately. Our experimental results match well with our numerical simulation using the Floquet method.